1. Field of the Invention
The present invention relates to image display technology using a display activated in a monochrome manner (hereinafter defined as “a monochrome image display”). Particularly the present invention relates to an image display method and an image display apparatus for enabling a plurality of pieces of monochrome image display to produce greater steps of gradation pixel display having a sub-pixel structure in a main-pixel using a single video card.
2. Description of the Related Art
An image for medical treatment purposes, captured (or measured) by medical diagnostic devices such as an ultrasound diagnostic device, a CT diagnostic device, an MRI diagnostic device, an X-ray diagnostic device, or Fuji Computed Radiography abbreviated by “FCR” which are trade marks, is treated if necessary by a various kinds of image processing, and after that, is printed out by means of a laser printer, a thermal printer or the like, so that the image is reproduced as a visible image on a film-shaped recording material and thus outputted as a hard copy.
The film on which the image for medical treatment purposes is reproduced is observed at the medical treatment site by means of a light box referred to as a schaukasten and thus used for various kinds of diagnoses.
Recently, an image for medical treatment purposes taken using a medical diagnostic device is reproduced on a display as a soft copy, with which the diagnosis is performed in this way.
Further, as a medical diagnostic device display, the Cathode Ray Tube (CRT) has currently been popular; however, further a liquid crystal display (LCD) has been being considered as a medical diagnostic display because they have many advantages of such as being easy to make the display compact, thin and light.
It is commonly known that an LCD can be driven in a digital manner. Recently, the DVI (Digital Visual Interface which is standardized by Digital Display Working Group) such as can transfer a digital signal to a display has widely been used, enabling the LCD panel to produce a high-quality picture image with no deterioration due to D/A signal conversion.
Further, in one of most popular digital image I/F, such as the DVI, a serial data transferring method known as Transition Minimized Differential Signaling (TMDS) is used.
In a system like this which employs DVI digital image data transfer, when a color image having 8 bits each forming R (red), G (green) or B (blue), there is a limitation to the number of pixels which can be dealt with: namely UXGA (1600×1200 pixels)—HDTV (1920×1080 pixels), and when an image is displayed on a display having a greater number of pixels, such as a QXGA (2048×1536 pixels) color LCD panel, the image data cannot be transferred fast enough.
Thus, the LCD panel is divided into two sections to display the image using the DVI to transfer the image data to the QXGA digital color LCD panel. FIG. 3 conceptually shows one example of this.
In the system shown in FIG. 3 there are an LCD 100 and a video card 30 connected to, by way of the DVI, the video card 30 being provided in a personal computer (PC) or the like which provides the image data to the LCD 100.
The QXGA color LCD panel 102 provided to the LCD 100 is divided into a right screen 102R and a left screen 102L, each having 1024×1536 pixels.
Further, the video card 30 has two output systems, a first link 32a and a second link 32b, and the first link 32a is corresponded to the right screen 102R, and the second link 32b is corresponded to the left screen 102L. Furthermore, each of the links of the video card 30 which transfers image data transfer by way of the DVI has three channels respectively corresponded to R image data, G image data or B image data, and has a clock signal output.
Based on the construction like this, the video card 30 transfers, from the first link 32a, the clock signal and the R, G and B image data, each having 8 bits corresponded to the right screen 102R of the LCD 100, and also, transfers from the second link 32b the clock signal and the R, G and B image data. Each having 8 bits corresponds to the left screen 102L.
As above-mentioned, the number of pixels of the right screen 102R and left screen 102L of the LCD panel 102 is 1024×1536 pixels, being equal to or less than that of a UXGA. Therefore, the image data transfer can be performed properly enough even by way of the DVI, and the image can be displayed on the QXGA color LCD panel 102.
According to a video card inserted into a Peripheral Component Interconnect bus (PCI bus) normally used in a PC, for example, only two DVI connectors can be mounted, due to circumstances pertaining to a physical limitation such as the substrate and connector sizes.
Therefore, at present, when the image data is transferred to the QXGA color LCD panel by the DVI, one video card (i.e., one “card”) is necessary for each LCD panel (i.e., one “head”) (referred to as a one-card-one-head system) When the image is to be displayed on two LCD panels, two video cards are necessary (referred to as a two-card-two-head system).
Diagnostic images of the images used for medical treatment purposes as discussed above, which are captured using the FCR or an X-ray diagnostic device, for example, are normally displayed as monochromized images.
Further, a panel section has been realized such as making the monochrome image LCD panel achromatic.
The color LCD panel has R, G and B sub-pixels by each main pixel, so that the LCD panel, which has been made to be monochromized, also has three sub-pixels. Further, when the image is displayed on such a monochrome image LCD panel, all the sub-pixels of a single pixel is normally driven (image data of each of all the sub-pixels of the single pixel is modulated) by the same image data.
In this monochrome image LCD panel, there is a notion of using this and the DVI image data transfer is used to display the image on two QXGA panels using one video card, resulting in having a one-card-two-head system realized. A conceptual diagram of one example of this is shown in FIG. 4.
As above-mentioned, the video card 30 for using the DVI has a two-system output having the first link 32a and the second link 32b. In the system in the shown example, the first link 32a is connected to a first monochrome image LCD 110, and the second link 32b is connected to a second monochrome image LCD 112. Further, like the previous example, the connections are made by way of the DVI.
In FIG. 4 the second monochrome LCD 112 is substantially as same as the first monochrome LCD 110. Thus the monochrome image LCD 110 is shown in detail as representation of the two.
As above-mentioned, the monochrome image LCD panel 114 of the monochrome image LCD 110 (112) is a QXGA panel which has been made monochrome by making the color filter of the color LCD panel achromatic (or colorless), and it is divided into a right screen 114R and a left screen 114L each having 1024×1536 pixels, as in the color LCD panel as above.
Further, the monochrome image LCD 110 has an image data developing unit 116R corresponded to the right screen 114R, and an image data developing unit 116L corresponded to the left screen 114L.
As above-mentioned, the monochrome image LCD panel 114 has three sub-pixels (hereinafter, referred to as a first pixel (1pix), a second pixel (2pix) and a third pixel (3pix)) corresponded to the R, G and B sub-pixels of the color LCD panel, and each sub-pixel is driven by the same image data, so that a monochrome image is displayed.
Therefore, if one piece of image data per a single pixel is transferred per one pixel and the transferred one is developed into three sub-pixels, then an image can be displayed on the monochrome image LCD panel 114.
In the shown example, in the first link 32a of the video card 30 (which is the same as the second link 32b) the channel which corresponds to the R image data transfers 8-bit monochrome image data to the developing unit 116R of the right screen 114R, and the channel corresponded to the B image data transfers 8-bit monochrome image data to the developing unit 116L of the left screen 114L, respectively.
Note that in the present example, the channel corresponded to the G image data is not used.
The developing unit 116R, having received the image data, develops this data (duplicating the data), generates three same sets of 8-bit image data and provides these sets to the monochrome image LCD panel 114 (i.e., monochrome image LCD panel 114's driver) as image data of the first pixel, second pixel and third pixel of the pixel corresponded to the right screen 114R, and thus the image is displayed. Similarly, the developing unit 116L also develops the image data which has been provided to it, generates three similar sets of 8-bit image data and provides these sets to the monochrome image LCD panel 114 as image data of the first pixel, second pixel and third pixel of the pixel corresponded to the left screen 114L, and thus the image is displayed.
That is, according to this method, by using two channels of a single link it becomes possible to display the image on a single QXGA monochrome image LCD panel 114.
Therefore, when both of the two links provided in the video card 30 are used, the image can be displayed on two monochrome image LCD panels 114, and on the QXGA monochrome panel it is possible to achieve a one-card-two-head system using image data transferred by way of the DVI.
As known, in the use of medical treatment application, there are many cases in which several images are to be displayed, such as photographic images of different portions of the same patient, or past and present photographic images of the same patient or the like. Therefore, there are many cases of vertically displaying an image (i.e., a “portrait”) while lining up two monochrome LCD's (i.e., monochrome image LCD panels) next to each other.
In an application such as this, one video card is sufficient for the one-card-two-head system, so that cost-performance is advantageously splendid.
Incidentally, in a monochrome display which has sub-pixels, as in the monochrome image LCD panel discussed above, it is possible to achieve greater steps of gradation by modulating image data of each of the sub-pixels individually as is disclosed in JP 11-311971 A and JP 11-352954 A by the assignee for the present application.
For example, in the above-mentioned monochrome image LCD panel being formed by a color LCD in which the color filter has been made to be achromatic, when each of the sub-pixels can be driven by 8 bits (i.e., 256 steps of gradation) it is possible to achieve display using gradation formed by 9.5 bits (i.e., 766 steps of gradation) on a single pixel having three sub-pixels.
In a medical application, in order to perform an accurate diagnosis it is necessary to have greater steps of gradation and higher picture quality image. Thus this method is extremely advantageous.
When this method is used to increase a number of step of gradation, if, e.g. the monochrome image LCD panel having the three sub-pixels is to be used to display an image formed by 9.5 bits then it is necessary for each of the three sub-pixels to be driven using the 8 bits separately and independently.
Therefore, in this case, when the DVI is to be used to transfer the data to display an image on the QXGA monochrome image LCD panel, then it is necessary to transfer the image data according to a method such as used in the case of the color LCD panel 102 shown in FIG. 3.
That is, when the sub-pixels are used to achieve the greater steps of gradation in this way, then it is not possible to achieve the one-card-two-head system as was used in the case shown in FIG. 4 in which the three sub-pixels are driven by the same image data. Accordingly, when images are displayed on two monochrome image LCD panels, there is no alternative but to adopt a two-card-two-head system, which increases cost.